Currently running ZCM 11.4.3 on a 2012R2 physical server, embedded database.
This is the only primary. Upgrading to ZCM 2017 shortly.

In order to have some redundancy, we are planning to add a 2nd primary. So
we were looking to see what the advice might be---set up another physical server
(we have one available) or do the appliance?

Any thoughts most welcome!
Regards, Chris G